Line-haul locomotives traditionally employed a single high-power internal combustion engine for driving the locomotive and supplying auxiliary demands. The duty cycle for these locomotives, however, required the engine to idle for long periods of time or the locomotive to maintain low train speeds. To improve fuel efficiency, reduce emissions, and prevent excessive wear and tear of a single large engine, many locomotive manufacturers now employ more than one engine to power a locomotive.
A modern multi-engine locomotive typically has two diesel engines, including a larger primary engine and a smaller auxiliary engine. Either one or both engines generate power to propel the locomotive. For example, at low throttle settings, only the smaller engine operates to provide power while the larger engine is turned off. At intermediate throttle settings, only the larger engine operates to provide power while the smaller engine is turned off. And at the highest throttle setting, both engines operate to provide power to the locomotive.
Multi-engine line-haul locomotives operate in a variety of environments, including in cold weather with ambient temperatures dipping below the freezing point of water. In such conditions, the engine coolant, typically water or a water-glycol mixture, may freeze causing damage to the engine block or to other engine components. Moreover, a cold engine may be unable to generate sufficient power because of inefficient fuel combustion at low temperatures.
One attempt to address the problems described above is disclosed in U.S. Pat. No. 6,636,798 of Biess et al. that issued on Oct. 21, 2003 (“the '798 patent”). In particular, the '798 patent discloses an auxiliary power unit made up of a secondary small engine for warming a non-operational primary engine. According to the method disclosed in the '798 patent, coolant from both the secondary engine and the primary engine is circulated through a heat exchanger in which coolant from the secondary engine transfers heat to coolant from the non-operational primary engine. In addition, the '798 patent discloses that electrical heaters are used to augment heating of the primary engine coolant by the heat exchanger.
Although the '798 patent discloses a system and a method of warming a primary engine using heated coolant from a smaller secondary engine, the method disclosed in the '798 patent requires additional electrical heaters to adequately heat the primary engine. These additional heaters not only make the system of the '798 patent more expensive, but also add complexity. Moreover, the '798 patent does not disclose any method of keeping the secondary engine warm in cold weather conditions after it has been turned off. Thus, when both the primary and the secondary engines of the '798 patent are non-operational, there may be a delay in starting of the primary engine because of the time initially required to heat and start the secondary engine and the time subsequently required by the secondary engine to heat the primary engine.
The engine warming system of the present disclosure solves one or more of the problems set forth above and/or other problems in the art.